Can you have multiple major plotlines in a single novel?

[ColGray]

I feel like this is a staple of modern literary fiction, but you don't see it so much in SF/F.

If you go on MSWL, anything labeled "family saga" means exactly this. Total Lit trope with the intention that the two completely divergent plots will collide in the climax.

A Plot is Timeline 1, Setting 1, Culture 1, Character Set 1-A, Arch-Plot 1-A, Themes 1, 2, 3
B Plot is Timeline 2, Setting 2 (Diaspora), Cultural 1-Diaspora, Character Set 1-B <crossover, but older, main cast is young>, Arch-Plot 1-B, Theme 2, 3, 4

Crescendo is the convergence and realization that A and B plots are related, history repeats itself, resolutions are different.

Also, this might be the most cynical view of literary tropes imaginable, but, "family saga" as a descriptor is now an immediate pass for me. It's been mined to death and individual flourishes of prose or culture are interesting, but insufficient to warrant the time commitment.

 

[Toby Frost]

The closest thing I can think of like this are films like Traffic, where several stories of equal importance are presented on a similar theme. In Traffic, the characters cross paths but don't get together as a "party". Some epic fantasy probably works this way, too, although I would expect the stands to meet more often and be less distinct.

 

[ColGray]

Fantasy and SF regularly do a thing where an unrelated character is trickled in as a way to world build, but the underlying intention is that they will join the overall main "party" at some point and this gives the reader grounding for this new character before they appear.

The Blade Itself does this with Ferro. She's a secondary POV character introduced midway through the first book with maybe 1 chapter for every 5 main POV chapters. She is on a different continent, doing different things, but slowly moving elsewhere. Her story is connected by theme and tertiary character overlap, but her A Plot is wholly separate. She joins the main party at the end of the book.

The Blade Itself kind of a does a magic trick overall, though: the first book in a trilogy, nearly the entire book is spent gathering the characters into a party to ready them for a Hero's Journey (copyright: J. Campbell) in the second book. The reader keeps thinking, Oh, they'll come together here. Ooooor here. Or here? And then, when they do, it's the end of the book! It completely undermines the standard expectation that the party forms and then off they go adventure and turning this trope on its head works--but I haven't seen it executed like that before or since.